| Author | Message | ||
     981099 Username: 981099 Registered: 04-2003 |
ethanol & propanoic acid are heated together under reflux . The main purpose of using the condenser is ?? | ||
| Samson Username: 981125 Registered: 04-2003 |
請問哪兒見到這題目? | ||
| 981099 Username: 981099 Registered: 04-2003 |
past paper | ||
| Samson Username: 981125 Registered: 04-2003 |
要造esterification好像唔使under reflux(本書無話要) | ||
| Inamoto5 Username: admin Registered: 04-2003 |
It is very common to do esterification under reflux.. The condenser is used to cool down the vapour of the reaction mixture. This vapour will change back to liquid state and then flow back to the reaction flask. | ||
| 981099 Username: 981099 Registered: 04-2003 |
1)the element in the same group of periodic table have similar physical property ? 2)the reaction between methane & bromine under light is violent ? 3) soapless detergent is acidic ? | ||
| 魚"mo"仔~Michael Username: 981087 Registered: 04-2003 |
1) not similiar, It's a gradual change of physical property 2) I don't know violent or not. But no light means no reaction | ||
| 迪 Username: 981001 Registered: 04-2003 |
how to change in physical property in same group of periodic table ? b.p. & m.p? 還有什麼? | ||
| 迪 Username: 981001 Registered: 04-2003 |
And why soapless detergent is acidic ? | ||
| 迪 Username: 981001 Registered: 04-2003 |
係唔係因為有 S | ||
| Chio U Kim Username: cuk Registered: 04-2003 |
Soapless detergent by itself is neutral because it is a salt of a strong alkali and a strong acid. The common soapless detergents are slightly acidic (pH ~ 5) because of the presence of acidic additives. Soapy detergent by itself is slightly alkaline because it is a salt of a strong alkali and a weak acid. |